In the use of an implement on a work vehicle, it is desirable to position the implement and a frame supporting said implement closely to the front of said vehicle for improved balance and stability during vehicle operations. The apparatus of U.S. Pat. No. 4,221,267 which issued to Jerrold R. Asal et al on Sept. 9, 1980 provides for controlled positioning of the frame and implement while maintaining satisfactory implement operation and minimizing weight of the associated elements. The present invention relates to a pivot connection which provides for universal type of motion of the implement with respect to the supporting frame.
U.S. Pat. No. 2,950,550 which issued on Aug. 30, 1960, to J. L. French discloses a tractor blade movably connected to a blade supporting subframe by plates movably positioned in tracks of the blade. The subframe is pivotally connected to the main or C-frame of the vehicle and accommodates tilting and angling of the blade. U.S. Pat. Nos. 3,083,480 and 3,084,461 which issued on Apr. 2, 1963, to L. Kirchler and on Apr. 9, 1963, to J. J. Beckford, respectively, also disclose embodiments of a blade connected to a supporting subframe which is connected to a main or C-frame.
U.S. Pat. No. 3,670,825 which issued to J. Asal et al on June 20, 1972, discloses a vehicle blade having a subframe member pivotally connected thereto and to a main or C-frame. The subframe member moves in positioning plates on the blade for positioning the subframe ends relative to the blade.
For example, a track-type tractor commonly has a frame mounted blade for performing various earthmoving or pushing operations. The blade is generally tiltable about a longitudinal axis of the vehicle or frame and movable through various angles relative to the tractor in a plane passing through said axis. These tilt and angle adjustments provide for the controlled positioning of the blade for more flexible use in the varying situations encountered during work operations. Hydraulic cylinders commonly perform these tilt and angle operations with the cylinders being connected to the frame and blade in preselected locations.
The blade is most commonly connected to and supported by a main or C-frame of the associated tractor. The hydraulic cylinders which "angle" the blade are each positioned between a respective track and the body of the tractor. In "tilting" the blade, the angle cylinders, of necessity, move laterally and can interfere with the tracks or body of the vehicle owing to their connection to the blade. This lateral movement limits the degree of tilt available and necessitates positioning the blade and forward portion of the C-frame an undesirable distance from the tractor in order to maintain satisfactory tilt and angle parameters. The resultant weight forward of the tractor can also decrease stability and balance of the vehicle for certain operations.
In some blade assembly embodiments, the blade has been mounted to a subframe which is in turn pivotally connected to the main or C-frame. The subframe thus supports the blade. The angle cylinders are connected to the C-frame and to either the subframe or the blade, but the tilt cylinders are connected to said subframe and the blade. This subframe arrangement tends to provide greater freedom of tilting and angling. However, the weight of the subframe necessary to support the blade, plus lateral movement of the angling cylinders if connected directly to the blade, also can decrease stability and balance of the vehicle and limit blade movement necessary for some operations.
Many blade assemblies which have angling and tilting capabilities have pivot connections between the blade and the frame which allow two degrees of pivot motion of the blade. However, when the blade is angled and then tilted, or vice versa, the blade binds and will not simultaneously perform the two functions.
The present invention is directed to overcoming one or more of the problems as set forth above.